Cup blanking and forming method and tooling therefor



.1970 J. D. HAWKINS ETAL 3,543,55

CUP BLANKING AND FORMING METHOD AND TOOLING THEREFOR FiledDed. 25, 19683 Sheets-Sheet 1 INVENTORS JERRY D. HAW S BILL G.R

Dec. 1, 1970 HAWKlNs E TAL. 3,543,559

CUP BLANKING AND FORMING METHOD AND TOOLING THEREFOR Filed Dec. 25, 19683 Sheets-Sheet 2 2 INVENTORB v JERRY D. HAWKINS BILL e. REID Dec. 1,1970 D, w ms ETAL 3,543,559

CUP BLANKING AND FORMING METHOD AND TOOLING THEREFOR Filed Dec. 23, 1968VENTORS JER D. HAWKINS BILL 3 Sheets-Sheet 8 I G. REID United StatesPatent 3,543,559 Patented Dec. 1, 1970 3,543,559 CUP BLANKING ANDFORMING METHOD AND TOOLING THEREFOR Jerry D. Hawkins, Country ClubHills, and Bill G. Reid, Bolton, 11]., assignors to Continental CanCompany, Inc., New York, N.Y., a corporation of New York Filed Dec. 23,1968, Ser. No. 785,899 Int. Cl. B21d 51/48 US. Cl. 72-335 ClaimsABSTRACT OF THE DISCLOSURE A method of forming a corrugated crown caphaving an uncorrugated lip at an angle to the flange, and compoundtooling for forming the cap in a double-acting press. The methodcomprises gripping the margin of the blank with predetermined pressure,draw forming and corrugating the skirt and flange while constricting themarginal portion of the blank, under restraint of the grip, thenrestraining the flange, leaving the lip free, and bending the lip. Thetooling includes blanking and forming punches in a first assembly, and anested die set in a second assembly. The blanking punch and an anvilgrip the margin of the blank, while the forming punch, telescoped in theblanking punch, coacts with the forming die, telescoped in the anvil, todraw and corrugate the skirt and flange, constricting the marginalportion of the blank under restraint of the grip. The grip pressure ispredetermined by a spring biasing the anvil toward the blanking punch.At the completion of the draw, a shoulder on the forming punch restrainsthe flange against the upper face of the forming die. Continued downwardmotion of the forming punch bends the lip between the anvil bore and acollar on the forming punch.

BACKGROUND OF THE INVENTION Field of the invention The invention relatesto mass production of crown caps in presses of the multi-action type,with compound tool and die sets. The invention relates more particularlyto a method and tooling for blanking and forming such caps having asmooth, uncorrugated lip extending at an angle to the corrugated flangeor web.

The prior art There is a large demand for small crown caps, of which thecap for a beverage bottle is a representative example. The basic contourof the standard crown cap is a cup with a generally horizontal flange,the flange being adapted for crimping to hold the crown tightly on thebottle top. Usually, such crowns are corrugated along the skirt andflange for stiffening effect. Crowns have heretofore been successfullymass-produced at low cost in gang punch presses by means of compoundtool and die sets which punch blank discs from the strip material andthen form and corrugate the caps by drawing the discs dropping down fromthe blanking operation.

It is a usual characteristic of crowns formed by the most economicalmethods of the prior art that when the flange thereof is crimped on thebottle finish the sharp edge of the rim stands away from the bottle.Consequently, a person grasping the cap may cut his fingers on theprojecting edge. This condition is particularly dangerous with twistcrowns. It has been proposed so solve this problem by curling the rim ofthe flange or skirt in order to protect or tuck the edge, so thatpersons handling the finished product will not suffer cut fingers.Alternatively, it has been proposed to coin, tumble, roll or similarlybreak or round the edge, which is inherently sharp by virtue of shearingfrom thin sheet metal, The various such proposals heretofore made forsolving the edge problem have involved additional material for the part,special materials, extra operations and set-ups, or all of these, with aresultant substantial increase in the cost of the article. In the caseof crown caps, competitive conditions have precluded adoption of thesubstantially more costly cap forms on any large scale. There is widedemand for a cap of the protected edge, or no-cut type, but at little orno premium over the less satisfactory caps now in general use.

It has been proposed to form a twist-type crown cap with a smooth lip atsuch angle to the cap flange that the lip assumes a position with theedge inward of the smooth lip and is protected thereby, when the cap iscrimped. However, heretofore there has been no satisfactory method oftooling for economically producing such smoothlip caps in quantity.

SUMMARY OF THE INVENTION It is an object of this invention to provide amethod of forming crown caps having a narrow, uncorrugated lip portionbent at a substantial angle to the plane of the flange, which method canbe practiced economically in mass production.

It is a further object of this invention to provide tool ing forblanking and forming crown caps or similar articles from sheet metalaccording to the method of this invention, where in the operations ofblanking, flanging, drawing and lip bending can be performed in asingle, rapid stroke, without transferring the part, yet minimizingmachine and tool cost, tool breakage and wear.

It is a still further object of this invention to provide a method andtooling for making crown caps of a type requiring forming and bending anarrow, uncorrugated lip portion relative to the flange, which methodand tooling can be readily incorporated and practiced in high speedpresses of the type in general use for making such crowns, which iseconomical of material, and which retains the basic configuration andproportions of the cap for closure in accordance with usual practices.

The foregoing and other objects and advantages of the novel method areachieved by gripping the marginal portion of the blank to restrainconstriction of the marginal portion, while draw forming the cap paneland skirt, and forming corrugations inwardly of the gripped portion,then restraining the flange, inwardly of the lip portion, againstbending relative to the skirt, leaving the lip portion free, and thenbending the lip portion relative to the flange. The cut edge diameter ofthe blank exceeds that of a conventional crown at most by the smallamount required to form the narrow lip. A crown formed according to themethod and with the tooling of this invention has the generalconfiguration and crimping characteristics of crowns as heretofore made,but has a lip bent to an angle which assures a protected position forthe edge when the crown is crimped on a bottle.

The tool assembly according to this invention need be little or nolarger than assemblies for making conventional crowns. The tooling canbe incorporated into press equipment in normal use for conventionalcrown forming, without major modification in mounting, set-up, or thegeneral mode of press operation. The additional compounding for thesequence required to blank and form according to this invention isprovided in the tooling itself by a novel design and arrangement of thepunch and die parts, whose operation requires little or no greaterstroke or pressure than required to form crowns as heretofore made.

The prior practice in mass-production tooling for crown caps generallyinvolves duplexing the blanking punch and the forming punch fordouble-action. The blanking punch knocks the blank down to the formingdie. The forming punch and die then form and corrugate the skirt andflange, which latter is constituted by the constricted marginal portionof the blank. In this prior practice, the corrugations inherently extendto the edge of the cap.

In tooling according to this invention, the marginal portion of theblank is gripped between the blanking punch and an anvil surrounding theforming die, while the skirt is drawn and corrugations are formed, themarginal portion constricting under restraint of the grip. The grip ismaintained on the lip portion substantially until the corrugations areformed inwardly of the lip portion. The flange is then restrainedbetween a shoulder on the forming punch and the upper face of theforming die, leaving the lip portion free, whereupon continued motion ofthe forming punch carries the cap and forming die downward relative tothe outer anvil, bending the lip portion between the anvil bore and acollar on the forming punch.

The foregoing and other features, objects and advantages of theinvention will be best understood from the following description and theaccompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary verticalsection through an article representative of those which may be producedaccording to the method and tooling of this invention;

FIG. 2 is a vertical section through a tool assembly constructed andarranged according to this invention, shown in position at initiation ofthe blanking stage, also fragmentarily showing associated press parts,die block and strip guide, the view being divided as FIGS. 2A and 2B, topermit use of a satisfactory scale;

FIG. 3 is a fragmentary vertical section similar to FIG. 2, showing theposition of the tools after a blank has been severed and gripped,preparatory to draw form- 8;

FIG. 4 is a fragmentary section, similar to FIG. 3, showing the positionof the tools and condition of the part at the completion of the drawforming operation;

FIG. 5 is an enlarged fragmentary plan view of a portion of the dieassembly shown in FIGS. 24 inclusive, showing details of the provisionsfor corrugation form- FIG. 6 is a fragmentary top plan view of the capin its condition at the stage of FIG. 4;

FIG. 7 is an enlarged fragmentary section through a portion of the toolassembly as in the position of FIG. 4; and

FIG. 8 is a fragmentary section similar to FIG. 4, showing the positionof the tools and condition of the part at the completion of the lipbending operation;

DESCRIPTION OF THE PREFERRED EMBODIMENT The method of forming articlesaccording to this invention will be best understood by describing themethod in association with preferred tooling for practicing the methodin mass production, that being the principal application of the method.However, it will be understood that the method of operation to producearticles of the desired characteristics is not limited to the particulartooling shown and described.

FIG. 1 shows the general configuration of an article of the form forwhich the method and tooling according to this invention areparticularly adapted. The article here shown is a crown cap having theform of a shallow cup, with a slightly crowned or dished panel 10, acylindrical wall or skirt 11, a flange 12, extending outwardly fromskirt 11, and a narrow. lip 13, which extends nearly at right angles toflange 12 in a direction away from panel 10. A plurality of corrugationribs 9 extend between skirt 11 and flange 12, terminating inwardly oflip 13. The cap is here shown inverted from the position in which it isnormally seen in use, the position shown being that in 4 which thearticle appears in subsequent drawings illustrating the productionmethod and tooling.

FIG. 2 shows a tooling assembly, or die set, constructed and arrangedaccording to this invention for high-speed production of caps as shownin FIG. 1. FIG. 2b is a downward continuation of FIG. 2a. Those skilledin the art of blanking and forming small articles from sheet metal willreadily understand that the tooling assembly as shown in FIG. 2 may beganged in line, or in a ring, whereby to produce a number of likearticles in simultaneous operation of the several sets in one machineassembly. It is a significant feature of the method and toolingaccording to this invention that same may be implemented in suchgang-press arrangement for economical, high-production operation.

In FIG. 2 only so much of the press is shown as assists in understandingthe operation sequence as shown here and in the subsequent views. Thepress parts shown include a bed 15 and a ram 16. Ram 16 is associatedwith suitable toggle mechanism or the like (not shown), constitutingwith bed 15 a press of the double-acting type, as well known forperforming combined blanking and forming operations in a set ofcomplementary tool assemblies. Die block 17, resting on bed 15, supportsa suitable strip guide, generally indicated by the reference numeral Thefirst, or punch, assembly consists of the blanking punch, sleeve 19, andthe forming punch 20, which carries an ejector pin 21. Sleeve 19 isactuated by ram 16 pressing on shoulder 22 of the clamping sleeve 23, inwhich sleeve 19 is held by means of clamping nut 24.

In FIG. 2 the position of the parts is that prevailing on the downwardstroke of ram 16, just as sleeve 19 severs a blank 8 from the strip 7,in the first stage of double action. Forming punch 20 and the seatingrod 21 are in retracted position, ready for downward stroke under effectof second-stage punch actuation.

The second, or die, assembly, held in die block 17, consists principallyof the blanking die 25, a gripping anvil 26 and the forming die 27,which carries an ejector anvil 28. Blanking die 25 is fitted to dieblock 17 by means of clamping screws or bolts 29. The other die membersare nested in blanking die 25, with clearance for assembly, adjustmentand for relative axial motion as hereafter more particularly described.

In the position of FIG. 2, no downward pressure has been brought to bearon the movable die parts, which are thus at their uppermost position.Ejector anvil 28 is biased to its upward position by spring 32, thelimit of upper position being determined by the adjustment of the stopand jam nuts 33, 34 at the lower end of rod 35, projecting downward fromthe head of anvil 28. Forming die 27 and anvil 26 are supported on andbiased upward by the heavy pressure spring 36, which rests on bushing 37in the bolster 38. At its upper end, spring 36 bears on pad 39, formingthe lower end of the yoke 40, which is an extension of the body of theforming die 27. Shoulder 61 of pad 39 bears on bed insert 71, andshoulder 31 of forming die 27 bears on and suports anvil 26. Yoke 40also houses the ejector anvil spring 32. Shoulder 41 serves as a limitto the downward motion of ejector anvil 28.

Referring now to FIG. 3, sleeve 19 has completed its blanking stroke andsevered blank 8, which is here supported around its marginal portion byanvil 26. The stroke of sleeve 19 and upper position of anvil 26- are sorelated that the clearance between sleeve 19, at full downward stroke,and anvil 26 is less than the minimum thickness of any blank 8. Assleeve 19 approaches the limit of its stroke, blank 8 is gripped betweensleeve 19 and anvil 26, 'whereafter, on the final increment of stroke,sleeve 19 pushes anvil 26 downward, against the bias of pressure spring36. Clearance accommodates this downward movement of anvil 26 and alsoprovides allowance for a possible double blank, which may occur in highspeed operation, due to failure of part ejection after the previousstroke. Otherwise, bottoming of anvil 26 on insert 49 may result incrushing or breaking sleeve :19, or other tool parts.

By virtue of anvil 26 bearing on shoulder 31 of die 27, the latter movesdownward with anvil 26. As best seen in FIG. 2, the downward thrust onanvil 26 and die 27 is yieldably opposed by spring 36, acting throughpad 39 and yoke 40, supporting die 27. By selected setting of bushing37, the spring 36 may be preloaded to a desired value corresponding tothe optimum gripping pressure along marginal portion 79 of blank 8,between sleeve .19 and anvil 26, for a purpose hereafter shown.

Referring again to FIG. 3, the forming punch 20 is at its firstoperational position, clamping the center of blank 8 on ejector anvil28, preparatory to draw forming. Ejector pin 21, advanced under biasingaction of spring 42 (FIG. 2A), provides pre-seating pressure and apredisposing bias of blank 8 toward level position upon concave anvilface 44, opposing the correspondingly crowned nose 43 of punch 20. Atthis stage the top faces 56, 57 and 58 of anvil 26, die 27 and anvil 28respectively present a continuous level support for blank 8, the membersbeing so disposed by virtue of the stop shoulder 31 of die 27 and thelimiting stop nut 33 (FIG. 2B) on rod 35, extending from anvil 28.Spring 32, supporting crowning anvil 28, being lighter than spring 36(FIG. 2B), biasing die 27 and anvil 26, permits anvil 28 to movedownward relative to die 27 and anvil 26, as punch 20 and anvil 28 drawthe center of blank 8 into die 27. The cupping draw tends to causewrinkling or buckling of the cap material in formation of the skirtportion. In the formation of crown caps, the buckling action isaccommodated by al lowing material to flow into suitable die pockets 52,54, establishing the corrugation ribs typical of such caps. However, therestraint effected upon the marginal portion 79 of blank 8 by grippingbetween punch 19 and anvil 26, under pressure corresponding to bias ofspring 36, obviates the development of corrugations in the gripped blankportion. The gripping pressure or restraint is established by means ofspring 36, as before described, so that the marginal annulus constrictsat substantially the same rate as the draw rate of skirt 11, that is,the gripping pressure exerted on blank 8 between sleeve 19 and anvil 26is less in amount than that to tension the material to its yield pointin drawing skirt 11. Thus, the material is not substantially stretchedin the draw, and skirt 11 will not be subject to substantial necking. Inmaking the representative bottle cap here shown, a total grippingpressure on the order of 1,000 lbs. has been found suitable.

From comparison of FIGS. 3 and 4 it will be seen that as draw formingproceeds and marginal portion 79 (FIG. 3) constricts, the area of thegripped annulus decreases at the rate of draw. By virtue of the constanttotal grip pressure being etfective on decreasing area, the unitpressure on the lip portion 80 increases, as the material therein isdrawn toward the upper face 55 of forming die 27. In the stage of FIG.4, the forming punch 20 is at its second operational position, drawforming being complete. Further travel of forming punch 20 relative toforming die 27, is precluded by virtue of shoulder 45 of crowning anvil28 bottoming in yoke 40*, supporting die 27 The provisions forcorrugating are best seen in FIG. 5. Spaced grooves 52 are cutlengthwise of cavity wall 53 of die 27. In draw forming, between thestage of FIG. 3 and the stage of FIG. 4, the material constituting theflange 14, and the portion of skirt 11 adjoining flange 14, for asubstantial length toward panel 10, are constricted from the outerannulus of blank 8. The constriction involves a gathering effect,accompanied by tendency to buckle and corrugate in a fairly regularpattern. The die grooves '52, 54 accommodate the buckled material in theform of corrugation ribs 9 (FIG. 1), which extend between skirt 11 andflange 12. The gathering effect being minimal in the portion of skirt 11toward panel 10, and further inhibited by panel 10, no corrugationsdevelop in that skirt portion.

In the course of the draw forming, the lip portion 80, is under anincreasingly intense gripping pressure, as above described. The pressurenot only prevents buckling or corrugation during the draw andconstriction, but so inhibits the transmission of the corrugationstresses and strains that substantially no stresses and strains subsistin lip portion 80. Therefore, even after lip portion is freed ofrestraint, substantially no blemish develops, the surfaces retaining atleast the smoothness of the original material, in fact enhanced bywiping under the pressure of the grip restraint during constriction ofthe margin. The restraint is maintained substantially until thecompletion of forming and corrugating, resulting in the capconfiguration at the stage of FIG. 4, as shown in FIG. 6, with ribs 9extending between skirt 11 and flange 12, and lip portion 80 free ofcorrugations.

The relative positions of the lip portion, flange and skirt to theseveral tool elements, at the stage of FIG. 4, is best seen in FIG. 7.Flange 12 is capture and restrained between shoulder 47 of punch 20 andupper face 55 of forming die 27. Lip portion 80 is resting substantiallyfree on upper face 52 of anvil 26, below counterbore 65 in sleeve 19.That is, lip portion 80' is free of the restraint upon flange 12 andvirtually free of the grip between sleeve 19 and anvil 26. Desirably,the diameter of counterbore 65 is such as nearly corresponds to, or isslightly smaller than, the average diameter of edge 14 at the stage hereshown, the edge diameter being necessarily subject to a small variationwith variation in the cut edge diameter from piece to piece, with toolwear, and with other variations in the material and tool operation. Aspreviously observed, the grip on lip portion 80 is maintainedsubstantially until completion of corrugation. After the drawcorrugation has progressed to substantial extent, in the mannerpreviously described, the buckling stresses are so relieved by formationof the ribs in skirt and flange that no substantial deleterious effectresults, should lip portion 80 be relieved from its grip just before thefinal small increment of draw, as may occur with a minimum cut ed-gediameter.

The continuing downward stroke of punch 20 from its position in FIGS. 4and 7 carries with it forming die 27 and the captured workpiece, againstthe bias of spring 36 (FIG. 2B). The weight of anvil 26 and pressure oflip portion 80 moves anvil 26 the distance permitted by remainingclearance 60, whereupon anvil 26 bottoms on shoulder 64 of insert 49,and fully frees the grip on lip portion 80. Further downward movement ofthe workpiece under impetus of punch 20 bends the lip portion 80 betweenthe collar 50* of the punch 20 and the bore 51 of anvil 26. FIG. 8 showsthe condition at completion of the stroke. Clearance to accommodate theedge 14 is provided by counterbore 65 in sleeve 19, the counterborediameter being such that, with anvil 26 downward, edge 14 will clear thecorner 86; as lip por-' tion 80 bends up.

Since the lip portion of the material has been maintained free ofwrinkling or corrugation stress, as described in connection with FIGS.3, 4 and 5, blemishing is substantially obviated in formation of the lip13. The cap is thus completed to the configuration of FIG. 1, with asmooth, unblemished lip 13. Also, there is substantially no scufiingalong corrugation ribs 9. This scuif-free condition in the corrugationareas derives principally from the arrangement and operation wherein thedraw forming of the skirt and the corrugations is complete and the capis captured between forming punch and forming die, before bending of thelip begins, as above described. Thus, there is no relative motion underpressure, between the cap, the forming die and the forming punch, afterthe corrugations are formed, and substantially no working,

Wiping, cocking or the like of the flange or skirt, under pressureexerted in bending the lip.

After lip 13 is formed, the several movable punches and die partsretract or return to their ready positions and the strip material 7 isadvanced for the next blanking and forming stroke. As forming punch 20retracts, ejector pin 21, under bias of spring 42 (FIG. 2A), frees thecap from punch nose 43. Ejector anvil 28, under bias of sping 32, forcesthe cap from die 27.

The foregoing description of a preferred embodiment is given by way ofexample. Those skilled in the art will be enabled thereby to devisevariations and modifications within the spirit and scope of theinvention as defined by the claims.

We claim:

1. In a method of forming a crown cap from a disc blank of sheetmaterial, said cap including a cover panel, a skirt extending from saidpanel, a flange extending laterally outward from said skirt,corrugations extending between said skirt and said flange, and anuncorrugated, inclined lip extending from said flange outwardly of saidcorrugations, the steps of:

(a) gripping said blank along a marginal portion thereof to restrainsaid marginal portion substantially uniformly against constriction, andto hold said blank in a plane;

(b) applying draw forming means, with pressure normal to said plane,against a portion of said blank inwardly of said marginal portion, toform said panel, said skirt and said corrugations, while constrictingsaid marginal portion against said gripping restraint, to form saidflange and a lip portion outwardly of said flange portion from the outerportion of said marginal portion, and maintaining said grippingrestraint along said lip portion outwardly of said corrugations untilsaid corrugations are substantially fully formed;

(c) restraining said flange inwardly of said lip portion against bendingrelative to said skirt, leaving said lip portion substantially free ofrestraint; and

(d) applying bending means against said lip portion to bend said lipportion relative to said flange, whereby to form said uncorrugated,inclined lip.

2. In a method of forming a crown cap, the steps according to claim 1,including applying said draw forming pressure to said blank in onedirection normal to said plane, and applying said lip portion bendingmeans against said lip portion with pressure on said lip portion in adirection opposite to said one direction, whereby to form said lipinclined from said flange in a direction away from said skirt and saidpanel.

3. In a method of forming a crown cap, the steps acccording to claim 1,including controlling said gripping restraint for exerting pressure uponsaid marginal portion in an amount to inhibit transmission ofcorrugation stresses and strains into said lip portion, said amountbeing less than that to tension said material in said drawforming beyondthe yield point of said material, whereby to constitute said lipsubstantially free of blemish and said skirt substantially free ofnecking.

4. In a method of forming a crown cap, the steps according to claim 2,including applying the total said gripping pressure initially along anannulus of said marginal portion, near the edge thereof, said marginalportion including said lip portion, said marginal annulus having aradial extent not less than the radial extent of said lip portion, andapplying said total pressure by means of rigid gripping members withradially fixed grip surfaces opposed along an annulus having an innerdiameter substantially equal to the diameter of said edge at completionof said constriction, whereby to increase the amount of said grippingpressure upon unit area of said lip portion along said edge during saiddrawing and said corrugating, relative to unit pressure upon said lippor- 8 tion subsisting upon initial application of said total pressure.

5. Apparatus for forming a crown cap from a disc blank of sheetmaterial, said cap including a cover panel, a skirt extending from saidpanel, a flange extending laterally outward from said skirt,corrugations extending between said skirt and said flange, and anuncorrugated, inclined lip extending from said flange outwardly of saidcorrugations, said apparatus comprising: first and second toolassemblies containing relatively reciprocable means for performing workupon said blank, including complementary gripping means for grippingsaid blank substantially continuously along an annular marginal ortionthereof; complementary draw forming means in said assemblies, coaxialwith said gripping means, including first forming means in said firstassembly movable between a retracted position and first, second andthird operational positions, and second forming means in said secondassembly cooperable with said first forming means, as said first formingmeans moves between said first and second operational positions, forforming said panel, said skirt and said corrugations, while constrictingsaid marginal portion under restraint of said gripping means toestablish said flange and an uncorrugated lip portion outwardly of saidflange, said lip portion being substantially freed from said grippingmeans, with said first forming means at said second operationalposition; and complementary lip bending means in said assemblies,including first bending means in said first assembly and second bendingmeans in said second assembly, arranged for coaction, to bend said lipportion relative to said flange, upon movement of said first formingmeans between said second and third operational positions, whereby toconstitute said crown cap with said uncorrugated lip.

6. Apparauts according to claim 5, wherein said assemblies includecomplementary blanking means, coaxial with said gripping means and saidforming means, for severing said blank from said material.

7. Apparatus according to claim 6, wherein said blanking means includesa blanking die in said second assembly, said gripping means including asleeve in said first assembly movable between a retracted position and agripping position, for coaction with said blanking die to sever saidblank, and for following said blank, while said sleeve moves betweensaid retracted and gripping positions.

8. Apparatus according to claim 7, said gripping means including ananvil in said second assembly having an annular upper face for opposingsaid sleeve and said marginal portion of said blank, said anvil beingmovable between a first position and a second position, said first anvilposition being that for said anvil to intercept said blank and saidsleeve at a sleeve position between said retracted position and saidgripping position less distant from said gripping position than anamount equal to the thickness of said blank; and said second assemblyincluding yieldable means for biasing said anvil to said first anvilposittion with a predetermined bias value, whereby to adapt saidgripping means for gripping said marginal portion with a pressurecorresponding to said bias value.

9. Apparatus according to claim 8, said first forming means having anose and a collar defining with said nose a shoulder set back from theend of said nose; said sccond forming means having a cavity for coactionwith said nose to form said panel, said skirt and said corrugations, assaid first forming means moves between said first and second operationalpositions, and an annular upper face for coaction with said shoulder torestrain said flange in a generally planar attitude substantially assaid first forming means attains said second operational position.

10. Apparatus according to claim 9, including stop means for limitingmovement of said anvil toward said second anvil position, and forestablishing said second anvil position at a distance from said firstanvil position at least equal to the maximum thickness of said blank,whereby to obviate incidence of said gripping pressure in an amountgreater than the amount corresponding to said bias value.

11. Apparatus according to claim 10, including means for releasablyengaging said second forming means with said anvil, with said upperfaces of said anvil and said second forming means coplanar, and foraccommodating movement of said anvil and said second forming meanstogether between said first and second anvil positions, under pressureof said first forming means upon said second forming means overcomingsaid bias, said second forming means being telescoped in said anvil inposition for said upper face of said second forming means to back saidblank when said anvil is at said first position and while said first andsecond forming means coact to draw said skirt and to form saidcorrugations.

12. Apparatus according to claim 11, wherein said yieldable means isarranged for action against said second forming means and for coactionwith said engaging means to bias said second forming means and saidanvil together toward said first anvil position, unidirectional limitmeans being arranged for engaging said anvil in opposition to said bias,to establish said first anvil position, the value of said bias beinggreater than the value of force exerted upon said second forming meansopposite to said bias, as said first forming means moves between saidfirst and second operational positions, said bending means including abore in said anvil arranged for coaction with said collar to bend saidlip portion, in a direction away from said panel, with said anvil atsaid second position, upon movement of said first forming means betweensaid second and third operational positions, and while said shoulder andsaid upper face of said second forming means restrain said flange insaid attitude.

13. Apparatus according to claim 12, including a counterbore in saidsleeve for freely accommodating the peripheral portion of said lipportion, while said bending means bend said free lip portion relative tosaid flange in a direction away from said panel and said skirt andtoward said sleeve at its said gripping position.

14. Apparatus according to claim 12, wherein said bias value correspondsto a grip pressure upon said marginal portion of an amount to inhibittransmission of corrugation stresses and strains into said lip portion,said amount being less than that to tension said material to its yieldpoint in draw forming said skirt, as said first forming means movesbetween said first and second operative positions, whereby saidapparatus is adapted to constiute said crown cap with said lipsubstantially free of blemish and said skirt substantially free ofnecking.

15. Apparatus for forming a crown cap from a disc blank of sheetmaterial, said cap including a cover panel, a flange extending laterallyoutward from said skirt, corrugations extending between said skirt andsaid flange, and an inclined lip extending from said flange outwardly ofsaid corrugations, said apparatus comprising: first and second t'oolassemblies containing relatively reciprocable means for performing workupon said blank; complementary draw forming means in said assemblies,said draw forming means including first forming means in said firstassembly sequentially movable, between first, second and thirdpositions, and second forming means in said second assembly adapted forcooperation with said first forming means to form said panel, saidskirt, said flange and said corrugations, as said first forming meansmoves between said first and second positions, and to restrain saidformed blank between said first and second forming means in relativepositions thereof substantially to preclude bending of said flangerelative to said skirt and bodily movement of said formed blank and saidfirst and second forming means relative to each other, leaving a lipportion of said blank outwardly of said flange free of said restraint,upon completion of said forming and during movement of said firstforming means between said second and third positions; and complementarylip bending means in said assemblies, including first bending means insaid first assembly and second bending means in said second assembly,said first and second bending means being arranged for coaction to bendsaid lip portion relative to said flange, upon movement of said firstforming means between said second and third p0- sitions, whereby tomitigate scuffing along said corruga tions while bending said lip.

References Cited UNITED STATES PATENTS 2,251,433 8/1941 Wareham 113-1212,605,730 8/ 1952 Dennis 72-348 3,258,954 7/1966 Dennis 72-335 RICHARDJ. HERBST, Primary Examiner

